AVIF

AVIF is a file format for images, meaning a defined way in which a photo is stored in a file. It can be recognized by the “.avif” extension at the end of the file name. It serves the same purpose as the better-known formats JPEG and PNG, but usually requires less storage space. A typical photo saved as AVIF is often only half the size of the same photo saved as JPEG, without looking noticeably worse. The format was developed by an alliance of major technology companies, including Google, Netflix, and Mozilla. It is freely usable: anyone who uses it does not have to pay any license fees.

Why smaller image files save money

The largest part of what gets loaded when opening a website is images. Text weighs almost nothing, whereas a single product photo can quickly amount to several hundred kilobytes. If an online shop delivers a thousand images and each of them becomes half the size, a large portion of its data volume is cut in half. This lowers the costs for the servers and the connections through which the data flows.

For users, loading time matters most. Pages that appear slow are abandoned more often, and search engines rank fast pages more favorably. On a weak mobile network, the difference between two and four seconds is clearly noticeable. That is why switching to AVIF is one of the simplest measures for many companies to make their website faster.

On top of that comes a quality argument. AVIF can store more color gradations than JPEG and supports HDR, meaning images with particularly bright highlights and deep shadows. It also supports transparency, for which PNG files used to be needed. One format thus replaces two older ones.

A video technique applied to still images

AVIF is not an entirely original invention from scratch. It uses the compression technology of the AV1 video format. Compression means: rewriting data so that it takes up less space. Technically, an AVIF image is a single still frame from an AV1 video, packaged in its own file container.

The trick behind this is called lossy compression. The process deliberately discards image information that the human eye barely notices. Subtle color differences in a uniformly blue sky go unnoticed by anyone, whereas fine edges in a face are noticed immediately. AV1 therefore distributes its data budget unevenly and places it where it becomes visible. JPEG does essentially the same thing, but works with methods from the early 1990s.

The price for the better quality is computing time. Creating an AVIF image takes several seconds depending on the settings, whereas JPEG takes milliseconds. This is manageable because an image is only compressed once but displayed millions of times. Displaying it is fast, because modern processors and graphics chips can often decode AV1 directly in hardware.

AVIF in the browser and in tech news

In everyday life, one usually encounters AVIF without noticing it. All widely used browsers, namely Chrome, Firefox, Safari, and Edge, now display the format. Large websites automatically deliver AVIF when the browser understands it, and a JPEG otherwise. Anyone who saves an image from a website may sometimes find an .avif file on their hard drive afterward.

This is exactly where the weakness shows up too. Older image editing programs, some office applications, and some print shops cannot handle AVIF. In that case, the only solution is to convert the file to JPEG. This problem is becoming smaller, but it is disappearing slowly.

In tech news, AVIF often appears in comparison with WebP and JPEG XL. WebP is the older Google proposal and compresses somewhat worse than AVIF. JPEG XL is technically considered very strong, but is supported by fewer browsers. Which format will prevail in the long run is still an open question, which is why the decisions of individual browser makers are being closely watched.